Method of manufacturing beta-ionone



United States Patent 7 3,475,764 METHOD: OF MANUFACTURING B-IONONE Jan Pot, Van Houtenlaan, Weesp, Netherlands, assignor, by mesne assignments, to U.S. Philips Corporation, New York, N.Y., a corporation of Delaware No Drawing. Filed Oct. 24, 1967, Ser. No. 677,773 Claims priority, applicaigonslilzeherlands, Oct. 26, 1966,

1m. or. con 49/61 U.S. Cl. 260-587 4 Claims ABSTRACT OF TIE DISCLOSURE Pseudo-ionone cyclized to ,B-ionone bysulfuric acid in the presence of liquid sulfur dioxide. The temperature of the reaction is controlled by evaporation of said sulfur d1- oxide. I

clyclization of pseudo-ionone in a heterogenous system built up of sulphuric acid and a liquid saturated hydrocarbon is described, mentions that a reaction at .20 to C. yields predominantly fi-ionone and at to +25 C. predominantly a-ionone.

The cyclisation reaction is strongly exothermal. Consequently, in order to manufacture predominantly fi-ionone not only the reactants must be cooled to temperatures below 0 C. but also the reaction heat must be dissipated instantaneously. A very cold cooling medium must therefore be used which require the use of a large quantity of expensive frigories in addition to a costly apparatus, or the reactants must be mixed together so slowly that only little heat is produced per unit time in a reactionmedium of large volume. In the latter case a less complicated cooling apparatus or a less cold cooling medium may be used.

Another important factor is the composition of the reaction medium. In principal the reaction may be carried out in100% sulphuricacid. The reaction mixture is then, however, too viscous to obtain a'g'ood mixture of the reactants. In addition'oxidation and sulfor'iation may occur as side reactions. It is therefore desirable to dilute the'sulphuric acid with a suitable solvent. Royals, Ind. Eng. Chem., 38, 546-548 (1946) has shown that with strong dilution of sulphuricacid by polar solvents such as water and acetic acid both the yield of ionone and the content of fi-ionone therein strongly decrease. Krishna J. Org. Chem, 22, 224-225 (1957) confirms this but shows that the dependency of the yield 'of B-ionone upon the degree of dilution is still greater than Royals has found. Conse quently, according to British patent specification 843,751, 93-100% sulphuric acid is used for the manufacture of p-ionone, while according to Dutch patent application 298,958 93-98% sulphuric acid diluted with 7 /210% by weight of lower aliphatic alcohol is used.

Thus it could not be expected that a high yield of fl-ionone is obtainable from pseudo-ionone in a medium containing, in addition to sulphuric acid, an amount by weight of a polar solvent which is up to several times greater.

Thus it was a surprise to find that if the polar sulphur dioxide is used to dilute sulphuric acid to such a strong Patented Oct. 28, 1969 extent, pseudo-iononecan be cyclized to form fi-ionone in that medium.

The use of sulphur dioxide also gives a surprising simplification and saving in adjusting and maintaining the desired temperature of reaction. The reactants can now be brought to the desired low temperature in a, simple manner by mixing them with liquid sulphur dioxide of, for example, room temperature, in which process the sulphur dioxide evaporates, while the reaction mixture can be maintained at the selected temperature, i.e., a temperature between the boiling point of sulfur dioxide and room temperature in the same manner. The escaping gaseous sulphur dioxide can be collected and compressed, it being possible to dissipate the heat of condensation, for example, by using water or air of, for example, room temperature. The liquid sulphur dioxide can thereafter be recyclized.

In order to be able to work up the formed fi-ionone by extraction with a suitable solvent, the reaction mixture is diluted with water according to the known methods. To prevent the temperature from increasing too much as a result of the hydration heat produced, the reaction mixture is poured out on ice or in ice water. If for the cyclization of pseudo-ionone use is made of the method described, then the manufacture can be effected in such manner that after completion of the reaction, suflicient sulphur dioxide to dissipate the hydration heat of the sulphuric acid is left in the mixture. Sulphur dioxide can alternatively be added prior to or during the pouring out in water.

It is therefore an advantage of the said method that frigories need not be used. Since sulphur dioxide is suitable ice 7 to dilute sulphuric acid therewith and can therefore be In additiOn the agent is cheap.

' In conformity therewith the present invention relates to a method of manufacturing fi-ionone in which pseudoionone is cyclised by means of sulphuric acid, and it is characterized in that the cyclization is carried out in the presence of sulphur dioxide.

It was found that the reaction can be carried out at' temperatures which lie between the boiling point of sulphur dioxide and room temperature. In conformity with what is known, it was, however, found that the yield of fl-ionone 1 decreases at higher temperatures. The reaction is therefore preferably carried out at temperatures between --10 C. and +10 C.

The concentration of the sulphuric acid was found to be allowed to vary rather strongly. The use of 90% to 98% sulphuric acid gave satisfactory results. For practical reasons 95%-96% sulphuric acid is, however, preferred.

Also the ratio between the quantities of sulphuric acid and pseudo-ionone may vary considerably. In general 200 mls. to 800 mls. of sulphuric acid preferably 400 mls. to 600 mls. are used per mol of pseudo-ionone.

The method may be used for manufacture of fl-ionone in batches but lends itself also excellently for continuous manufacture.

The reaction mixture may be worked up by pouring it out in water whereafter the S-ionone is extracted with a suitable solvent. It is, however, also possible to work up by pouring out in a mixture of water and a solvent, for example, petroleum ether.

The reaction time is of little influence on the yield of ,B-ionone. In general said time lies between 1 and 10 minutes, as a rule between 3 and 7 minutes.

3 EXAMPLE 1 50 mls. of liquid sulphur dioxide were added to 50 mls. of 95% sulphuric acid at room temperature, while stirring, whereupon the temperature decreased to between 4 C. and C. Subsequently 19.0 gms. of pseudoionone (content 94%) and 150 mls. of liquid sulphur dioxide of room temperature were simultaneously added to the sulphuric acid through a wide-necked funnel. Subsequently there was additional stirring for 5 minutes. The

content 13 95.8%, content a less than 1%, in a medium of 92% sulphuric acid.

EXAMPLES 4 UP TO AND INCLUDING 15 Sulphuric acid, pseudo-ionone and liquid sulphur dioxide, all of room temperature, were continuously led into a reaction vessel through separate channels which terminated near the bottom of the vessel. The cylindrical vessel was provided with a stirrer, a chimney for the temperature of the reaction mixture remained below removal of gaseous sulphur dioxide and an overflow to a 0 C. work-up vessel. The volume of the reaction mixture was The reaction mixture was subsequently poured out into 65 mls. 100 mls. of water of room temperature, the sulphur Water, petroleum ether, boiling point 40 C.60 C. dioxide still present cooling the mlxture. The mixture and sulphur dioxide, all or room temperature, were added was subsequently extracted twice with 100 mls. of petrocontinuously in the work-up vessel. The work-up vessel leurn ether, boiling point 40-60 C., whereafter the colwas also provided with a stirrer, chimney and overflow. lected extracts were washed with a 10% sodium carbon- The outflowing liquid was separated, washed and dried ate solution and then with a saturated sodium chloride analogous to the manner described in the preceding exsolution. After the extract was dried, the solvent was amples. After evaporation of the solvent, the yield and removed by distilling at reduced pressure. Yield of ionone the content were determined. The results are given in the 18.0 gms. Content of fl-ionone 95.4% (calculated from following table:

' TABLE Content Content Content 95% o! l -IOIlOllB inper- SOzin Yleldln inperinper- Temper- H2SO4 gmsJ cent of W container gms. 0! cent of 5- cent 01 aature mls./hour hour Ionone AkgsJhour ionone Ionone Ionone ln 0.

Example N0;

4 500 190 94 1 182 90 05 -7 500 10s 94 1. 2 132 90 0. 5 9 500 202 04 0.0 188 02 1 +10 500 202 04 1 0.5 184 81 12-3 +18 300 204 04 1. 2 192 03 1-1. 5 s 000 202 94 1.2 7 184 97 1 0 500 202 84 1.3 170 9r 0. 5-15 -9 700 200 84 1.2 182 s0 0. 51 8 1,000 s 94 2.0 312 92 1. 5-2 -s/10 250 102 34 0. 7 93 94 1-1. 5 -9 500 202 84 1.2 180 90 1 9 000 100 94 2.0 182 96 1 9/-10 1 98% of sulphuric acid. 9 Very large excess of S0 used.

U.V.-spectrum) content of a-ionone 0.5%1% (deter- What is claimed is: mined by means of thin-layer chromatography). 40 1. The method of manufacturing fl-ionone comprising EXAMPLE 2 cyclizrng pseudo-lonone With a mlxture consisting essentrally of about *200 to 800 ml. of 90% to 98% sulfuric 250 mls. of llqUlCi sulphur d1ox1de were added to I40 id 1 f theipseudoqonom i li i bging 0f 90% Sulphur: acld at room temperature Where" carried out in the presence of suflicient liquid sulfur diupon the temperature decreased t0 between -8 C. and oxidg so that a temperature between {11 of 9 C- 6 g 0f P P (Content 9 and sulfur dioxide :and room temperature is maintained by 400 mls. of l1qu1d sulphur d1ox1de of room temperature evaporation f said lf 'di id were added through a wide-necked funnel, whereafter 2 h h d f l i 1 h i thg li i i thCl'S was additional stirring for 5 minutes. The reaction carried out at a temperature betwggn about .1Q CI and temperature remained below 0 C. The reactionmixture +10 C. i Was Subsequently Poured out In P Watch 3. The method of claim 1 wherein the cyclization is sulphur dioxide still present C00ll1'1g the ;m1xtu.re. The carried out continuously, mixture was extracted twice with 300 mls. of petroleum The method f claim 1 wherein ft the reaction ether, bolllllg P0111t P Th eXtraCt$ were is completed the reaction mixture is' diluted with wamixed together, washed with a 10% sodium carbonate m d i id lfur di id solution and a saturated sodium chloride solution and subsequently dried. After evaporation of the. solvent 57 References Cited gms. ionone resulted consisting for 96% of ii-ionone, for less than /2 of u-ionone. FOREIGN PATENTS 50 1,030,946 5/1966 Great Britain.

EXAMPLE 3 In a manner identical to the method described in Example 2, ionone was manufactured in a yield of 92%,

BERNARD HELFIN, Primary Examiner M. M. JACOBS, Assistant Examiner 

